Mysterious object near Lobster Claw Nebula not visible in previous images - Forums

I shot the Lobster Claw Nebula last night (9/28/25). Stacked and Processed in Pixinsight. I used HOO pallete using Narrowband Normalization. 73× 3 minute exposures. After processing I noticed a “Whatzit” right below the nebula which, I believe, is star HD218997. Looks like a Planetary Nebula. Thing is, it isn’t on any other images I found on Astrobin and it isn’t on my image from last year. 📷 CropLobster1.jpgHere is the original image. Item is question is in the lower center of the image. 📷 Lobster Claw Nebula (SH2-157) 9/28/25

https://app.astrobin.com/i/7mel2n/

Same crop from my image from last year

📷 cropSH2_157.jpg

Huh, interesting. Either it's an artifact (very likely) or it's some sort of new feature that quite literally appeared last night (very unlikely), since recent images like this one don't seem to show it

I happen to have imaged that region last night. I haven’t stacked anything, but I looked through my SHO subs and I don’t see any traces of the ring that you show in your image around that star. That star does look a lot brighter and “bloatier” in the Ha channel compared to the Oiii channel.

If you are using a UV/IR filter or similar light pollution filter that is an interference filter and your optic is a very short focal length, this is what you will see. Especially if it is not of the highest quality filter. Typically seen around very red stars which happen to have a very high IR output. The defective filter, or inappropriate filter first fails to filter NIR wavelengths and second, the optic fails to focus those NIR well, hence the ring. The ring can be any color, because the Bayer color filters all fail to filter any IR.

Just to give more information:

If you want to see my description of the discovery of this artifact, see my post here: https://astrob.in/cd9mc1/0/

Note that the artifact always seem to happen with stars designated Long Period Variable stars. Because I had been testing NIR filters in imaging in some of my work posted on AstroBin, I often look at fields in the NIR data found on Aladin. That is how I learned that LPV stars have an exceptionally bright NIR/IR signature. Often what are fairly faint stars in the visible image, turn into the brightest stars in NIR/IR images.

So I looked up your star, and voila!, your star with the ring turns out to be a Mira Type Variable star. I’ll guess that this is likely a long-period variable.

But I don’t have to guess that it is a strong NIR star. See below:

Visible image: 📷 image.pngAt 2.16nm:

📷 image.pngNote that the signal at 2.16nm blows away the brightness that is seen by the brightest blue giant stars just to the right.

So you setup is ideally set up if you are into discovering Long Period Variables, Mira type variables, etc. Anything that is a very bright star in the NIR/IR bands.

Best,

Alan

AB won’t let me edit, but I wanted to say that the stars in the above cut and copy images don’t appear to align. But the red crosshairs actually establish the same position and the same star that you have trouble with. It is just because I was rushing to get the crops done.

This is my data from 20-09-2025. I think the object in your image is an artifact from your filter

It's an IR light leak from the L-Extreme.

Thank you for your replies. 👍️

I have noticed the same artifact in captures compared with last year as well. I captured roughly 10 hours in each Ha SII OIII with antlia Edge 4.5nm filters and the star appears much dimmer and smaller than the previous year’s acquisitions with the same equipment in each band. So much that the stacking rejection algorithm has produced severe ringing around the star which caused me to look a bit deeper. After research, there are several posters noting the same with various setups. Just chiming in to correct the filter artifact suggestions. This appears to be a LPV.

📷 Screenshot 2025-10-05 090854.jpgTaken 10/02/2025

📷 Screenshot 2025-10-05 090824.jpg

Taken 10/14/2024

Ron Bernknopf · Sep 29, 2025, 09:55 PM
I shot the Lobster Claw Nebula last night (9/28/25). Stacked and Processed in Pixinsight. I used HOO pallete using Narrowband Normalization. 73× 3 minute exposures. After processing I noticed a “Whatzit” right below the nebula which, I believe, is star HD218997. Looks like a Planetary Nebula. Thing is, it isn’t on any other images I found on Astrobin and it isn’t on my image from last year. 📷 CropLobster1.jpgHere is the original image. Item is question is in the lower center of the image. 📷 Lobster Claw Nebula (SH2-157) 9/28/25
https://app.astrobin.com/i/7mel2n/
Same crop from my image from last year
📷 cropSH2_157.jpg

Are you sure you didn’t integrate last year’s captures with this night’s? All of my captures from this year show the smaller sized star, but last year the star definitely appears larger and brighter. When I integrate the two, I also get the ringing, but just integrating this year’s I see no artifact.

Here’s a low quality video showing the star blinking high and low with a mostly random mix of 2024 and 2025 captures in OIII. The 2024 are bright, the 2025 are dim. The end of the sequence is all 2025.

2025-10-05 10-01-20.mp4

Too bad it was not something new! 😊 That would be much more exciting.

I noted something on an unfinished image I was working on today. It is really small and faint but does barely show on someone else’s image of the area with totally different equipment. I need to do some more database searches and see if it is a known object - so far nothing. It would be nice if there was a single and authoritative source that shows every known object of every kind and does so without endless searching about.

📷 image.pngI seem to have gotten the same thing! Taken 9/26 - 9/28/2025.

Darryn Waites · Oct 9, 2025, 12:03 AM
📷 image.pngI seem to have gotten the same thing! Taken 9/26 - 9/28/2025.

I’ll assume you have read the earlier posts above regarding the cause and solution to this. Certainly, if someone was interested in discovering long period variable stars, using an inappropriate LP or multi-band interference filter with a fast optic is the way to go!

What is surprising to me is when I first posted this issue (and solution) a couple years ago on my images and also in the forums, very few people seemed to acknowledge they also had the issue. I suspect my problem with the L-Pro filter has now translated to the recent proliferation of these new multi-band pass filters used with OSC cameras. It would be nice if the manufacturers of these filters would alert their customers as to their filters’ limitations.

Just looking into this more. I stacked this year’s frames in OIII totaling about 7 hours separately and there seems to be some very faint structure around the star. Maybe some are picking that up? In the color frames shared, the ring seems to be blue or white. I am imaging from bortle 9, so perhaps those with less light pollution can pick up more structure.

To summarize:

1.) The star appears to be a bright IR source, so IR leak is a possibility.

2.) The star appears to have been at a high point in luminosity around the same time last year and has since dimmed (at least evidenced by my sessions on the target with the same equipment).

3.) There appears to be some very faint structure around the star in the OIII band in my captures from this year (shared below).

What conclusions can we draw here?

📷 Screenshot 2025-10-08 224811.jpg

I think that you have confirmed the LPV nature of the star very well. I would have to ask if you have ruled out NIR leakage with your setup? I assume so, but you have not stated why you are sure you are not seeing NIR light leaking. I think you can assume no light leak if your optic is fairly long focal length and depending on, and if you are not using any LPF, etc.

I have often wondered what the connection is between LPV stars and their shocking brightness in the NIR and sometimes through the mid IR. Because NIR/IR light is a signal for heating, such as heating of dust to moderate temperatures, I am guessing that LPV stars likely have fairly closely associated dense dust structures around them. The stars heating of this dust causes the dust to re-emit light very efficiently in the NIR/IR. So if the halo that you see is real, and not NIR light leaking, then it may make sense if it is dust. However, your observation is much much fainter than what the others here have posted and what I have seen. In those cases, I think there is little doubt that what we have seen is light leak.

Alan Brunelle · Oct 9, 2025, 05:17 AM
I think that you have confirmed the LPV nature of the star very well. I would have to ask if you have ruled out NIR leakage with your setup? I assume so, but you have not stated why you are sure you are not seeing NIR light leaking. I think you can assume no light leak if your optic is fairly long focal length and depending on, and if you are not using any LPF, etc.
I have often wondered what the connection is between LPV stars and their shocking brightness in the NIR and sometimes through the mid IR. Because NIR/IR light is a signal for heating, such as heating of dust to moderate temperatures, I am guessing that LPV stars likely have fairly closely associated dense dust structures around them. The stars heating of this dust causes the dust to re-emit light very efficiently in the NIR/IR. So if the halo that you see is real, and not NIR light leaking, then it may make sense if it is dust. However, your observation is much much fainter than what the others here have posted and what I have seen. In those cases, I think there is little doubt that what we have seen is light leak.

I haven’t really ruled out NIR leak, but my captures were all at 714mm f7 with 4.5nm SHO filters.

I’m not real familiar with what NIR leak should look like, but I would assume with color cameras it should show in the red band? I’ve seen examples here and elsewhere that mostly show blueish ringing.

Reagen Gibson:
I haven’t really ruled out NIR leak, but my captures were all at 714mm f7 with 4.5nm SHO filters.

I’m not real familiar with what NIR leak should look like, but I would assume with color cameras it should show in the red band? I’ve seen examples here and elsewhere that mostly show blueish ringing.

Not really. All the NIR light leaks that I have witnessed (directly or indirectly) are in the higher frequency range thus bluish to violet.

andrea tasselli · Oct 9, 2025, 09:45 PM
Reagen Gibson:
I haven’t really ruled out NIR leak, but my captures were all at 714mm f7 with 4.5nm SHO filters.

I’m not real familiar with what NIR leak should look like, but I would assume with color cameras it should show in the red band? I’ve seen examples here and elsewhere that mostly show blueish ringing.

Not really. All the NIR light leaks that I have witnessed (directly or indirectly) are in the higher frequency range thus bluish to violet.

As Andrea stated, not in the red band. With color cameras, i.e. with Bayer matrix filters, above 800nm all those filters are transparent to the NIR photons. I have a NIR capable camera that when I put a 950nm or any filter above 800nm in front of the camera, my data, whether I debayer the data or not is gray scale. What the light leak halo will look like from a OSC camera in an otherwise color image, will look odd. I have seen in my images I get a whitish and bluish tinge and I’ve seen other colors. My guess is that what the color ends up being will be dependant on the debayer algorithm and how it does its work. In the area of the halo, all the pixels will record the NIR photons underneath the Bayer filter layer basically equally, This in addition to whatever other true visible light that the optic is sending to those same pixels.

FYI, my camera and its response:

📷 image.pngThe only other issue is the filters you used. I cannot say anything about your setup other than I have not used what you have and cannot speak to your halo or whether or not it is an artifact. To me it looks different than the artifact that I was addressing here.

Interesting to note. Thank you.

I am still pretty confident the elevated luminosity witnessed last year was the variable nature of the star, as it was clearly evident in last year’s captures with the same rig but now appears to be diminished.

I do not have any doubt about that. The star is listed as a variable. And if my memory serves me well, a type that could be a LPV to boot. And I would not be surprized that there are other types of strong IR emitters that will cause issues with my filter and telescope!

Reagen Gibson · Oct 9, 2025, 10:24 PM
Interesting to note. Thank you.
I am still pretty confident the elevated luminosity witnessed last year was the variable nature of the star, as it was clearly evident in last year’s captures with the same rig but now appears to be diminished.

One thing that would be interesting would be to look into how the variability of this sort of star changes in VIS (picking a color such as the standard blue or violet that is used to study variables) and then seeing if the brightness changes in NIR parallel the vis or if they are different. I would think if they behaved differently, that would argue for the variability being due to the cloud environment rather than just the star changing brightness.

If you look into my earlier postings you will find where I discuss wanting to do surveys of stars in areas of dense dust using a dual camera setup tplook for just this sort of thing, among other phenomena. https://astrob.in/g9a5ee/0/ I failed, but also ran out of time to pursue this fully. Nor do I live in an area that would make this practical.

I had this artifact recently as well in two of my Hyperstar images that used the L-eXtreme f/2 filter. I took concluded it was an artifact from the filter. An IR leak would seem to make sense.

I first noticed it in my Cygnus Wall image.

I then noticed it again in my Eastern Veil image.

You can see in my descriptions my own adventure of trying to figure out what it could be.

I used SetiAstroSuite’s What’s in my image and realized they were all long period variable stars, and concluded that somehow, those objects interact with the L-eXtreme in such a way to produce the artifact. So an IR leak or some other defect of the filter would make the most sense. Certainly not a defect in the stars! 😂

David Foust · Oct 10, 2025, 01:52 PM
I had this artifact recently as well in two of my Hyperstar images that used the L-eXtreme f/2 filter. I took concluded it was an artifact from the filter. An IR leak would seem to make sense.
I first noticed it in my Cygnus Wall image.
I then noticed it again in my Eastern Veil image.
You can see in my descriptions my own adventure of trying to figure out what it could be.
I used SetiAstroSuite’s What’s in my image and realized they were all long period variable stars, and concluded that somehow, those objects interact with the L-eXtreme in such a way to produce the artifact. So an IR leak or some other defect of the filter would make the most sense. Certainly not a defect in the stars! 😂

That totally makes sense. Thank you for this explanation. Glad to see that someone else experienced the same issue. I love using the L-eXtreme but will look for this in my future images.